Idomeneus, King of Crete
King Idomeneus (ldomeneo) has sent prisoners from Troy back to Crete, including Ilia, King Priam's daughter.
Unknown to Idomeneus, Ilia and Idamantes (Idamante), Idomeneus's son, are in love, and Idamantes is also loved by Elektra (Elettra).
Idomeneus is set to return to Crete, at which point the prisoners will be granted amnesty, but a storm forces him to offer to Neptune a sacrifice of the first living thing he meets as he steps ashore. This turns out to be his son.
Idomeneus tries to avoid his obligation to Neptune by sending Idamantes to Argos as an escort for Elektra. But Neptune raises a terrible storm out of which appears a monster which then begins to tear the island apart.
The people realize that someone has offended the gods, and Idomeneus confesses.
Idamantes prepares to battle with the monster. Before doing so he tells Ilia that he loves her.
The jealous Elektra bursts in with Idomeneus, who then tells of his vow to Neptune. Idamantes kills the monster, then offers himself in fulfilment of his father's promise to Neptune.
The voice of Neptune intervenes, sparing Idamantes' life, but demanding that Idomeneus abdicate. ldamantes duly takes the throne, with Ilia at his side.